C# WaitCallback类代码示例

 /// <summary>
 /// constructor
 /// </summary>
 public WebcamVisionThreadGrabFrameMulti(WaitCallback callback, object data, bool loop)
 {
     if (callback == null) throw new ArgumentNullException("callback");
     _callback = callback;
     _data = data;
     _loop = loop;
 }

	internal AsyncResult (WaitCallback cb, object state, bool capture_context)
	{
		async_state = state;
		async_delegate = cb;
		if (capture_context)
			current = ExecutionContext.Capture ();
	}

        // Main executing of commands
        internal string Execute(string clientId, string sessionId, string commands, string callback)
        {
            Log(clientId, sessionId, commands);

            string newSessionId = TTE.NewSessionId();

            try {
                string cleanCommands = _statementProcessor.Clean(commands);
                string[] splitCommands = _statementProcessor.Split(cleanCommands, false);
                ArrayList instantiatedCommands = _statementProcessor.Instantiate(splitCommands, clientId, newSessionId, callback);

                foreach (CommandContainer command in instantiatedCommands) {
                    command.OrigSessionId = sessionId;
                    _commandProcessor.Create(command);
                }

                // The callback value should be a http, https or tcp connection string, this will be called when the process has stopped running
                if (callback != "") {
                    WaitCallback wc = new WaitCallback(ProcessCommand);
                    ThreadPool.QueueUserWorkItem(wc, newSessionId);
                } else {
                    ProcessCommand(newSessionId);
                }
            } catch (Exception ex) {
                Log(ex); _messageProcessor.Create(clientId, newSessionId, Config.ClientId, enmMessageCategory.Exception, ex.Message);
            }

            return newSessionId;
        }

		/// <summary>
		/// Timer initialization
		/// </summary>
		/// <param name="workFunction">Job working function</param>
		/// <param name="workingPoints">Working time points</param>
		public ServiceJob(WaitCallback workFunction, IList<DateTime> workingPoints)
		{
			if (workingPoints == null) throw new ArgumentNullException("workingPoints");

			Execute = workFunction;
			WorkingPoints = workingPoints;
		}

        public void Open()
        {
            if (listenSockets == null)
            {
                listenSockets = new List<Socket>();
                if (!ipAddress.Equals(IPAddress.Broadcast))
                {
                    listenSockets.Add(CreateListenSocket(this.ipAddress, this.port, multicast));
                }
                else
                {
                    listenSockets.Add(CreateListenSocket(IPAddress.Any, this.port, multicast));
                    if (Socket.OSSupportsIPv6)
                    {
                        listenSockets.Add(CreateListenSocket(IPAddress.IPv6Any, this.port, multicast));
                    }
                }
            }

            this.onReceive = new AsyncCallback(this.OnReceive);
            WaitCallback startReceivingCallback = new WaitCallback(StartReceiving);

            Socket[] socketsSnapshot = listenSockets.ToArray();
            for (int i = 0; i < socketsSnapshot.Length; i++)
            {
                ThreadPool.QueueUserWorkItem(startReceivingCallback, socketsSnapshot[i]);
            }
        }

 // ctor
 internal RequestQueue(int minExternFreeThreads, int minLocalFreeThreads, int queueLimit) {
     _minExternFreeThreads = minExternFreeThreads;
     _minLocalFreeThreads = minLocalFreeThreads;
     _queueLimit = queueLimit;
     
     _workItemCallback = new WaitCallback(this.WorkItemCallback);
 }

		public WorkItem(WorkItemId taskID, WaitCallback wc, IAsyncResult state, ExecutionContext ctx)
		{
			_callback = wc;
			_state = state;
			_ctx = ctx;
			_taskID = taskID;
		}

 public virtual IMessageCtrl AsyncProcessMessage(IMessage reqMsg, IMessageSink replySink)
 {
     ADAsyncWorkItem item = new ADAsyncWorkItem(reqMsg, this, replySink);
     WaitCallback callBack = new WaitCallback(item.FinishAsyncWork);
     ThreadPool.QueueUserWorkItem(callBack);
     return null;
 }

 public override object BeginExecute(WaitCallback waitCallback, object state)
 {
     Thread result = new Thread(new ParameterizedThreadStart(waitCallback));
     result.IsBackground = true;
     result.Start(state);
     return result;
 }

 // this function adds an item to the queue, and takes care of updating the counters.
 // All functions added to the queue should be wrapped in this wrapper.
 public void QueueItemWrapper(WaitCallback workFunction, object parametersIn)
 {
     lock (counterLock)
     {
         queueLength--;
         analysisThreadCount++;
     }
     try
     {
         workFunction(parametersIn);
     }
     catch (Exception e)
     {
         // if there's an exception thrown while adding a block then we're
         // pretty much stuck. The best we can do is log it and eat it to
         // stop it killing the rest of the program.
         controller.log("Exception thrown analysing " + parametersIn.ToString());
         controller.errorLog("Exception thrown analysing " + parametersIn.ToString());
         controller.errorLog(e.ToString());
         controller.errorLog("======================");
         controller.errorLog("");
         return;
     }
     finally
     {
         lock (counterLock) analysisThreadCount--;
     }
     lock (counterLock)
     {
         totalAnalysed++;
         currentAnalysisTotal++;
     }
 }

		protected internal override void Schedule (WaitCallback callback, Guid workflowInstanceId, DateTime whenUtc, Guid timerId)
		{
			//WorkflowInstance wi = WorkflowRuntime.GetInstanceFromGuid (workflowInstanceId);

			//wi.TimerEventSubscriptionCollection.Add
			//	(new TimerEventSubscription (workflowInstanceId, timerId));
		}

 public static void Enqueue(WaitCallback callback, Policy policy)
 {
     switch(policy)
     {
         case Policy.Immediate:
             logger.Info("Immediately running callback {0}",
                 callback.Method.Name);
             ThreadPool.QueueUserWorkItem(new WaitCallback(callback));
             break;
         case Policy.Queued:
             lock (queue)
             {
                 if (cooledDown)
                 {
                     logger.Info("Immediately putting callback {0}",
                         callback.Method.Name);
                     ThreadPool.QueueUserWorkItem(
                         new WaitCallback(callback));
                 }
                 else
                 {
                     logger.Debug("Queuing callback {0} for later execution",
                         callback.Method.Name);
                     queue.Add(callback);
                 }
             }
             break;
     }
 }

 /// <summary>
 /// constructor
 /// </summary>
 public ThreadServerReceive(WaitCallback callback, dpslamServer server, ArrayList receive_buffer)
 {
     if (callback == null) throw new ArgumentNullException("callback");
     _callback = callback;
     _server = server;
     _buffer = receive_buffer;
 }

        /// <summary>
        /// This method takes as input the connection string to an SQL Server database
        /// and creates a corresponding SQLite database file with a schema derived from
        /// the SQL Server database.
        /// </summary>
        /// <param name="sqlServerConnString">The connection string to the SQL Server database.</param>
        /// <param name="sqlitePath">The path to the SQLite database file that needs to get created.</param>
        /// <param name="password">The password to use or NULL if no password should be used to encrypt the DB</param>
        /// <param name="handler">A handler delegate for progress notifications.</param>
        /// <param name="selectionHandler">The selection handler that allows the user to select which
        /// tables to convert</param>
        /// <remarks>The method continues asynchronously in the background and the caller returned
        /// immediatly.</remarks>
        public static void ConvertSqlServerToSQLiteDatabase(string sqlServerConnString,
            string sqlitePath, string password, SqlConversionHandler handler, 
            SqlTableSelectionHandler selectionHandler,
            FailedViewDefinitionHandler viewFailureHandler,
            bool createTriggers)
        {
            // Clear cancelled flag
            _cancelled = false;

            WaitCallback wc = new WaitCallback(delegate(object state)
            {
                try
                {
                    _isActive = true;
                    ConvertSqlServerDatabaseToSQLiteFile(sqlServerConnString, sqlitePath, password, handler, selectionHandler, viewFailureHandler, createTriggers);
                    _isActive = false;
                    handler(true, true, 100, "Finished converting database");
                }
                catch (Exception ex)
                {
                    _log.Error("Failed to convert SQL Server database to SQLite database", ex);
                    _isActive = false;
                    handler(true, false, 100, ex.Message);
                } // catch
            });
            ThreadPool.QueueUserWorkItem(wc);
        }

 //异步页面的任务启动方法
 public IAsyncResult OnBegin(object sender, EventArgs e,
     AsyncCallback cb, object extraData)
 {
     _proc = new WaitCallback(ChatInvokeProc);
     Hashtable theUser = new Hashtable();
     theUser = (Hashtable)extraData;
     string user = theUser["guid"].ToString();
     _guid = user;
     Thread.CurrentThread.Name = "上下文线程" + user;
     //用户处理，不存在则增加，即为登录
     theUser["asyn"] = this;
     theUser["lastUpdateTime"] = DateTime.Now.ToString();
     Hashtable feachUser = new Hashtable();
     bool isInCach=false;
     for (var i = 0; i < globalCache.userCache.Count; i++)
     {
         feachUser = (Hashtable)globalCache.userCache[i];
         if (theUser["guid"].ToString() == feachUser["guid"].ToString())
         {
             globalCache.userCache[i] = theUser;
             isInCach = true;
         }
     }
     if (!isInCach)
     {
         globalCache.userCache.Add(theUser);
     }
     //开始异步执行，这里会开启一个新的辅助线程
     return _proc.BeginInvoke(extraData, cb, extraData);
 }